From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA2D1C4363D for ; Wed, 23 Sep 2020 06:31:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62519221E8 for ; Wed, 23 Sep 2020 06:31:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eP8iqQnj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726647AbgIWGbs (ORCPT ); Wed, 23 Sep 2020 02:31:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60564 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726179AbgIWGbs (ORCPT ); Wed, 23 Sep 2020 02:31:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600842706; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jC7xykCrdkUMT9gFZ3QyUZCRmwNkMDA3HcJpGrglkA8=; b=eP8iqQnjD3AtFbIUHSLJf2CXD4No+CBU4UUiNzk3ICw6hgtWcZSk4+HLDTmrueZYVE/OlM YcUmUaQVTwElImzMjnas46md71wqvI+ulS0gHgONyxciLWeD4xiyNeaCwkW18FU8OJNRc8 wn+chOuqfGX83/ELj87B8foaIR98//M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-325-adDz4NVeMXC8L0K4fxJbxA-1; Wed, 23 Sep 2020 02:31:41 -0400 X-MC-Unique: adDz4NVeMXC8L0K4fxJbxA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AEA4418C9F40; Wed, 23 Sep 2020 06:31:39 +0000 (UTC) Received: from [10.64.54.30] (vpn2-54-30.bne.redhat.com [10.64.54.30]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 382767B7B3; Wed, 23 Sep 2020 06:31:37 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH V3 2/3] arm64/mm/hotplug: Enable MEM_OFFLINE event handling To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org Cc: Mark Rutland , Will Deacon , catalin.marinas@arm.com, Steve Capper , linux-kernel@vger.kernel.org, Mark Brown , Marc Zyngier , will@kernel.org References: <1600689908-28213-1-git-send-email-anshuman.khandual@arm.com> <1600689908-28213-3-git-send-email-anshuman.khandual@arm.com> From: Gavin Shan Message-ID: Date: Wed, 23 Sep 2020 16:31:34 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <1600689908-28213-3-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Anshuman, On 9/21/20 10:05 PM, Anshuman Khandual wrote: > This enables MEM_OFFLINE memory event handling. It will help intercept any > possible error condition such as if boot memory some how still got offlined > even after an explicit notifier failure, potentially by a future change in > generic hot plug framework. This would help detect such scenarios and help > debug further. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Mark Rutland > Cc: Marc Zyngier > Cc: Steve Capper > Cc: Mark Brown > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- I'm not sure if it makes sense since MEM_OFFLINE won't be triggered after NOTIFY_BAD is returned from MEM_GOING_OFFLINE. NOTIFY_BAD means the whole offline process is stopped. It would be guranteed by generic framework from syntax standpoint. However, this looks good if MEM_OFFLINE is triggered without calling into MEM_GOING_OFFLINE previously, but it would be a bug from generic framework. > arch/arm64/mm/mmu.c | 37 ++++++++++++++++++++++++++++++++----- > 1 file changed, 32 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index df3b7415b128..6b171bd88bcf 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1482,13 +1482,40 @@ static int prevent_bootmem_remove_notifier(struct notifier_block *nb, > unsigned long end_pfn = arg->start_pfn + arg->nr_pages; > unsigned long pfn = arg->start_pfn; > > - if (action != MEM_GOING_OFFLINE) > + if ((action != MEM_GOING_OFFLINE) && (action != MEM_OFFLINE)) > return NOTIFY_OK; > > - for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > - ms = __pfn_to_section(pfn); > - if (early_section(ms)) > - return NOTIFY_BAD; > + if (action == MEM_GOING_OFFLINE) { > + for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > + ms = __pfn_to_section(pfn); > + if (early_section(ms)) { > + pr_warn("Boot memory offlining attempted\n"); > + return NOTIFY_BAD; > + } > + } > + } else if (action == MEM_OFFLINE) { > + for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > + ms = __pfn_to_section(pfn); > + if (early_section(ms)) { > + > + /* > + * This should have never happened. Boot memory > + * offlining should have been prevented by this > + * very notifier. Probably some memory removal > + * procedure might have changed which would then > + * require further debug. > + */ > + pr_err("Boot memory offlined\n"); > + > + /* > + * Core memory hotplug does not process a return > + * code from the notifier for MEM_OFFLINE event. > + * Error condition has been reported. Report as > + * ignored. > + */ > + return NOTIFY_DONE; > + } > + } > } > return NOTIFY_OK; > } > It's pretty much irrelevant comment if the patch doesn't make sense: the logical block for MEM_GOING_OFFLINE would be reused by MEM_OFFLINE as they looks similar except the return value and error message :) Cheers, Gavin